JPH0737537B2 - Chitin film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a chitin membrane having excellent oxygen permeability, and more specifically, a contact lens material, a gas exchange membrane, a tissue culture substrate that can be worn for a long period of time. The present invention relates to a flat film-shaped or hollow fiber film-shaped chitin molded product useful as the above.

(Prior Art) The following is known regarding a film made of chitin or chitosan.

(1) The "semi-permeable membrane" of Japanese Patent Publication No. 57-14204 is manufactured by dissolving chitin in a mixed solvent of trichloroacetic acid and a halogenated hydrocarbon and coagulating the obtained chitin dope in a free state. Described above regarding the water permeability of the chitin membrane.

(2) Polymers, Vol.36, pp.175-181 (1979)
"Trichloroacetic acid-based chitin solvent and recycled chitin film"
Have examined the strength and elongation of a film obtained by drying it in a free state, Young's modulus, hygroscopicity, thermal stability, and the like.

(3) "Dialysis membrane with excellent permeability" disclosed in JP-A-54-139294 describes that a membrane having high solute permeability and mechanical strength was obtained from acetylated chitin by a solvent evaporation method. Has been done.

(4) In JP-A-59-116418, "Method for producing chitosan fiber and film", there is described the air flow rate of the film obtained by drying in a free state.

(5) by RAA Muzzarelli, published by Pergamon Press (1
(977) Page 71 of "CHITIN" compares the permeation performance of oxygen, nitrogen, and carbon dioxide between the chitosan membrane and the cellophane membrane.

(Problems to be solved by the invention) When a chitin membrane is cut and polished to be used as a contact lens, or when a chitin hollow fiber membrane is used as a cell culture substrate, the oxygen permeation performance when wet is extremely high. This is an important property.

However, flat membranes and hollow fiber membranes of chitin, which have excellent oxygen permeability when wet and are preferably used as a contact lens material or a substrate for cell culture, have not been known so far.

An object of the present invention is to provide a chitin membrane having excellent oxygen permeability when wet.

(Means for Solving the Problems) The inventors of the present invention have conducted extensive studies to achieve the above-mentioned objects, and as a result, from coagulation of chitin dope containing chitin having a specific degree of polymerization to a specific concentration to drying. The present inventors have found that the above-mentioned object can be achieved by a film obtained by carrying out the step (1) under a fixed length, and have reached the present invention.

That is, the present invention is composed of water-insoluble chitin and has an oxygen permeability coefficient of at least 1.0 × 10 ⁻¹⁰ cm ³ (STP) when wet.
The gist is a chitin film characterized by cm / cm ² · sec · mmHg.

The water-insoluble chitin that constitutes the membrane of the present invention is a crustacean,
Poly (N-acetyl-D-glucosamine) obtained by treating the exoskeleton of insects with hydrochloric acid and caustic soda to remove calcium and proteins.
Alternatively, it refers to a derivative that does not dissolve in water.
Examples of such chitin derivatives include those obtained by deacetylating a part of the acetylamino group of chitin, ether compounds, ester compounds, hydroxyethyl compounds, O-ethyl compounds, and the like, and specific examples include poly [N- Acetyl-6-O- (2-hydroxyethyl) -D-glucosamine], poly [N-acetyl-6-O- (ethyl) -D-
Glucosamine] and the like.

The chitin film of the present invention can be prepared by using a chitin dope containing chitin having a specific degree of polymerization at a specific concentration and performing the steps from coagulation of the dope to drying under a fixed length.

A preferred solvent for obtaining the chitin dope is, for example, a mixture of trichloroacetic acid and a halogenated hydrocarbon,
Examples thereof include a mixture of lithium chloride and dimethylacetamide, or a mixture of lithium chloride and N-methylpyrrolidone.

The relationship between the degree of polymerization of chitin used and the concentration of chitin in the dope greatly affects the oxygen permeability. That is, the lower the degree of polymerization of chitin and the concentration of chitin in the dope, the better the oxygen permeation performance. The preferred degree of polymerization of chitin is a solution obtained by dissolving it in dimethylacetamide containing lithium chloride at a ratio of 8 w / w% to a concentration of 0.4 w / w% using a B-type rotational viscometer. Viscosity at 30 ℃ measured is 10P or less, more preferably 5P or less, optimally 5
It is in the range of ~ 400cp.

The preferred chitin concentration in the dope varies depending on the degree of polymerization of chitin used, but is preferably 50 w / w% or less, more preferably 30 w / w% or less, most preferably 0.1 to 15 w / w%.

In order to carry out the steps from solidification of chitin dope to drying under a fixed length, for example, the following method can be adopted.

The chitin dope may be continuously and continuously applied to the outer peripheral portion of the solid material, dipped in a coagulation bath, and dried after the solidification as it is. In this case, as the solidification progresses, the solidified product contracts, and as a result, the solidified product does not separate from the outer periphery of the solidified product and is retained on the surface of the solidified product, that is, dried from the solidification under a fixed length. Up to. As a solid,
Any shape such as a spherical shape, a rod shape, a cylindrical shape, or a polygonal shape can be used, and the material thereof may be any solid as long as it is an inorganic or organic solid such as metal, glass, plastic, and wood. The thickness of the chitin dope applied to the outer peripheral portion of the solid depends on the concentration of the chitin dope and the thickness of the chitin film to be obtained, but is preferably 0.1 to 5
The range is 0 mm, more preferably 1 to 30 mm, and most preferably 2 to 20 mm.

In order to coagulate the chitin dope, it may be brought into contact with a coagulating liquid, and as the coagulating liquid preferably used, for example, alcohols such as methanol and ethanol, acetone,
Examples include ketones such as methyl ethyl ketone, dimethyl sulfoxide, and water, which may be used alone or as a mixed solution of two or more kinds. The temperature of the coagulating liquid is preferably in the range of 0 to 60 ° C., and the bath ratio is preferably 5 times or more the chitin dope capacity.

After coagulating with a coagulating liquid, an organic solvent treatment or a hot water treatment may be performed if necessary.

As a drying method, natural drying, hot air drying, vacuum drying or the like can be adopted, and the drying temperature is preferably in the range of 0 to 120 ° C.

The thickness of the chitin film of the present invention is 0.01 to 5 mm in the case of a flat film.
In the case of a hollow fiber membrane, the range is preferably 0.005 to 0.1 mm.

The chitin film of the present invention has at least 1.0 × 10 ⁻¹⁰ cm ³ (STP)
・ Oxygen permeability coefficient when wet of cm / cm ²・ sec ・ mmHg. The oxygen permeation coefficient when wet in the present invention means that the chitin membrane is immersed in deionized water or distilled water at about 25 ° C. for 6 hours or more to moisten, and then attached to an oxygen electrode in water saturated with oxygen gas. The amount of oxygen permeated through the chitin membrane was measured by the electrode method, and the obtained value was standardized (0 ℃, 760mmHg)
It is the value expressed in units of cm ³ (STP) · cm / cm ² · sec · mmHg after being converted to oxygen capacity.

(Example) Next, an example is given and the present invention is explained still more concretely.

Examples 1 to 8 and Comparative Examples 1 and 2 were dissolved in a dimethylacetamide solution containing lithium chloride at a ratio of 8 w / w% so that the concentration was 0.4 w / w%.
The viscosity at 30 ℃ (hereinafter referred to as solution viscosity) is 65.
Chitin powder with 0 cp was treated with 1N hydrochloric acid solution at 50 ℃ for different times to obtain solution viscosities of 13, 55 and 2 respectively.
Three different degrees of polymerization of 50 cp were obtained.

Using this chitin, various concentrations of chitin dope were prepared. That is, the raw material having a solution viscosity of 13 cp had a concentration of 5, 10, 15 (Examples 1 to 3) or 20 w / w% (Comparative Example 1), and the raw material having a solution viscosity of 55 cp had a concentration of 2, 5 or 8 w / w% (Example 4). ~ 6) concentration, 250c
The raw material for p was at a concentration of 1,3 w / w% (Examples 7,8) and 650 c
The chitin powder of p had a concentration of 2w / w% (Comparative Example 2),
A chitin dope was obtained by dissolving in a dimethylacetamide solution containing lithium chloride at a ratio of 8w / w%.

These dopes were continuously applied to the outer circumference of a glass cylinder having an outer diameter of 50 mm to a thickness of about 2 mm, immersed in methanol to solidify, and then repeatedly washed with water. After leaving it at room temperature for about 24 hours, it was vacuum dried at room temperature.

Table 1 shows the thickness, water content, and oxygen permeation coefficient in the wet state measured by the electrode method. Here, the water content is a value obtained from the following formula.

(W ₁ : Weight with water, W ₂ : Dry weight) From Table 1, it can be seen that the lower the solution viscosity and the lower the dope concentration, the greater the content rate of the obtained film and the oxygen transmission coefficient. Moreover, even if chitin with a low solution viscosity is used, is the chitin concentration in the dope too high?
It is also clear that if chitin having a low solution concentration and a high solution viscosity is used, a chitin membrane having an excellent oxygen permeability cannot be obtained.

Comparative Example 3 Among the steps for producing a chitin film, the properties of the film obtained without performing the drying step under a fixed length were examined.

The dope used in Example 1 was applied to the outer circumference of a glass cylinder having an outer diameter of 50 mm to a thickness of about 2 mm, immersed in methanol to solidify, and then repeatedly washed with water. After peeling the solidified product from the cylinder, it was left in the room for 24 hours and then vacuum dried at room temperature. The chitin film contracted significantly when dried.

The obtained film had a thickness of 1.32 mm, a water content of 51%, and an oxygen permeability coefficient of 0.85 × 10 ^-10 cm ³ (STP) · cm / cm ² · sec · mmHg.

(Effects of the Invention) The chitin film of the present invention has excellent oxygen permeability and a high water content, and therefore can be used as a soft contact lens that can be worn for a long period of time by cutting and polishing. In addition, it can be applied to oxygen-enriched membranes and tissue culture. By combining the excellent biocompatibility of chitin with high oxygen permeability, it is expected that the application of chitin membranes will be greatly expanded.

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Claims (1)

[Claims] 1. A water-insoluble chitin having an oxygen permeability coefficient of at least 1.0 × 10 ⁻¹⁰ cm ³ (STP) · cm / cm ² · when wet.
Chitin film characterized by sec · mmHg.